Pacing and sensing vectors

ABSTRACT

A method for allowing cardiac signals to be sensed and pacing pulse vectors to be delivered between two or more electrodes. In one embodiment, cardiac signals are sensed and pacing pulse vectors are delivered between at least one of a first left ventricular electrode and a second left ventricular electrode. Alternatively, cardiac signals are sensed and pacing pulse vectors are delivered between different combinations of the first and second left ventricular electrodes and a first supraventricular electrode. In addition, cardiac signals are sensed and pacing pulse vectors are delivered between different combinations of the first and second left ventricular electrode, the first supraventricular electrode and a conductive housing. In an additional embodiment, a first right ventricular electrode is used to sense cardiac signals and provide pacing pulses with different combinations of the first and second left ventricular electrodes, the first supraventricular electrode and the housing.

CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.11/554,146, filed on Oct. 30, 2006, now issued as U.S. Pat. No.7,945,325, which is a continuation of U.S. patent application Ser. No.09/779,754, filed on Feb. 8, 2001, now issued as U.S. Pat. No.7,130,682, the benefit of priority of each of which is hereby claimed,and each of which is hereby incorporated by reference herein in itsentirety.

TECHNICAL FIELD

The present invention relates to implantable medical devices, and moreparticularly to sensing and delivering energy pulses to and from thecoronary vasculature.

BACKGROUND

Cardiac pulse generator systems include a battery powered pulsegenerator and one or more leads for delivering pulses to the heart.Current pulse generators include electronic circuitry for determiningthe nature of an irregular rhythm, commonly referred to as arrhythmia,and for timing the delivery of a pulse for a particular purpose. Thepulse generator is typically implanted into a subcutaneous pocket madein the wall of the chest. Insulated wires called leads attached to thepulse generator are routed subcutaneously from the pocket to theshoulder or neck where the leads enter a major vein, usually thesubclavian vein. The leads are then routed into the site of pacing,usually a chamber of the heart. The leads are electrically connected tothe pulse generators on one end and are electrically connected to theheart on the other end. Electrodes on the leads provide the electricalconnection of the lead to the heart. The leads are used to sense cardiacsignals from the heart and to deliver electrical discharges from thepulse generator to the heart.

The electrodes are typically arranged on a lead body in two ways orcategories. A pair of electrodes which form a single electrical circuit(i.e., one electrode is positive and one electrode is negative)positioned within the heart is a bipolar arrangement. The bipolararrangement of electrodes requires two insulated wires positioned withinthe lead. When one electrode is positioned in or about the heart on alead and represents one pole and the other electrode representing theother pole is the pulse generator housing, this arrangement is known asa unipolar arrangement. The unipolar arrangement of electrodes requiresone insulated wire positioned within the lead.

In general, the heart can be divided into two sides, a right side and aleft side. Each side serves a specific function. The right side of theheart receives blood from the body and pumps it into the lungs toexchange gases. The left side of the heart receives the oxygenated bloodfrom the lungs and pumps it to the brain and throughout the body.

Typically, pacing and defibrillation leads are positioned within theright chambers of the heart, or positioned within the coronaryvasculature so as to position one or more electrodes adjacent a leftventricular region of the heart. From their positions within or adjacentto the ventricular chambers, the electrodes on the leads are used tosense cardiac signals and to deliver energy pulses in either a bipolaror a unipolar fashion. This sensing and pacing, however, is accomplishedonly within or across the chamber in which the lead is implanted. Thus,there exists a need in the art for providing additional options insensing and delivering electrical energy pulses to a patient's heart.

SUMMARY

The present subject matter provides for an apparatus and method forallowing cardiac signals to be sensed and pacing pulse vectors to beprogrammed for being delivered between two or more electrodes. In oneembodiment, the present subject matter allows for cardiac signals to besensed and pacing pulse vectors to be delivered between at least one ofa first left ventricular electrode and a second left ventricularelectrode in a left ventricular region. In an additional embodiment,cardiac signals are sensed and pacing pulse vectors are deliveredbetween different combinations of the first and/or second leftventricular electrodes in a left ventricular region and a firstsupraventricular electrode in a right atrial region. In addition,cardiac signals are sensed and pacing pulse vectors are deliveredbetween different combinations of the first and/or second leftventricular electrodes in a left ventricular region and a rightventricular electrode in a right ventricular region. In addition, thehousing of the apparatus is conductive so as to allow cardiac signals tobe sensed and pacing pulse vectors to be delivered between differentcombinations of the first and second left ventricular electrodes, thefirst supraventricular electrode, the right ventricular electrode andthe housing.

In one embodiment, the apparatus includes an implantable pulse generatorto which is attached a first lead and a second lead. The first leadincludes a first supraventricular electrode adapted to be positioned ina right atrial region, and the second lead includes the first and secondleft ventricular electrodes that are both adapted to be positionedadjacent a left ventricular region. The electrodes on the first andsecond leads are coupled to the implantable pulse generator and tocontrol circuitry within the implantable pulse generator. In oneembodiment, the control circuitry includes a pacing output circuit thatis programmable to control delivery of pacing pulses betweencombinations of the first and/or second left ventricular electrodes inthe left ventricular region and the first supraventricular electrode inthe right atrial region. In an additional embodiment, the pacing outputcircuit is programmable to control delivery of pacing pulses betweencombinations of the first and/or second left ventricular electrodes inthe left ventricular region and the right ventricular electrode in theright ventricular region.

Examples of the pacing vectors include delivering pacing pulses from thefirst left ventricular electrode as a cathode to the firstsupraventricular electrode as an anode. Alternatively, pacing pulses aredelivered from the first and/or second left ventricular electrode as acathode to the right ventricular electrode as an anode. In addition, thepacing output circuit delivers the pacing pulse between the first leftventricular electrode and the second left ventricular electrode in aleft ventricular region and the first supraventricular electrode. Inaddition, the control circuitry includes an extended bipolar crosschamber sensor that receives a cardiac signal sensed between the firstleft ventricular electrode and the first supraventricular electrode.Alternatively, the cardiac signal is sensed between the second leftventricular electrode and the first supraventricular electrode. Cardiacsignals sensed between other combinations of the electrodes, includingelectrodes in the right ventricle, are also possible.

In one embodiment, the first lead further includes a right ventricularelectrode adapted to be positioned in a right ventricular region.Cardiac signals are sensed and pacing pulse vectors are delivered fromvarious combinations of the right ventricular electrode, the firstsupraventricular electrode, the first and second left ventricularelectrodes and the housing. For example, the control circuitry directsthe pacing output circuit to deliver pacing pulses from the first leftatrial electrode as an anode to the right ventricular electrode as acathode. Alternatively, the pacing output circuit controls delivery ofpacing pulses between the first left ventricular electrode, or thesecond left ventricular electrode and the conductive housing. In anadditional embodiment, the pacing output circuit controls delivery ofpacing pulses between the first left ventricular electrode and thesecond left ventricular electrode and the right ventricular electrode,where the first and second left ventricular electrodes are common.Alternatively, the pacing output circuit controls delivery of pacingpulses between the first left ventricular electrode and the second leftventricular electrode and the right ventricular electrode and thehousing of the implantable pulse generator, where the first and secondleft ventricular electrodes are common and the right ventricularelectrode and the housing are common. In addition, the control circuitryallows for a cardiac signal to be sensed between one of the first andsecond electrodes and the right ventricular electrode and for pacingpulses to be delivered between one, or both, of the first and secondelectrodes and the right ventricular electrode.

Other combinations of sensing and pacing vectors are possible, as willbe more fully described below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is one embodiment of an apparatus according to the presentsubject matter that is implanted into a heart, from which segments havebeen removed to show detail;

FIG. 2 is one embodiment of an apparatus according to the presentsubject matter that is implanted into a heart, from which segments havebeen removed to show detail;

FIG. 3 is a block diagram of electronic control circuitry for oneembodiment of an apparatus according to the present subject matter;

FIG. 4 is one embodiment of an apparatus according to the presentsubject matter that is implanted into a heart, from which segments havebeen removed to show detail;

FIG. 5 is one embodiment of an apparatus according to the presentsubject matter that is implanted into a heart, from which segments havebeen removed to show detail;

FIG. 6 is a flow chart of a method according to one embodiment of thepresent subject matter;

FIG. 7 is a flow chart of a method according to one embodiment of thepresent subject matter;

FIG. 8 is a flow chart of a method according to one embodiment of thepresent subject matter;

FIG. 9 is a flow chart of a method according to one embodiment of thepresent subject matter; and

FIG. 10 is a block diagram of electronic control circuitry for oneembodiment of an apparatus according to the present subject matter.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that structuralchanges may be made without departing from the scope of the presentinvention. Therefore, the following detailed description is not to betaken in a limiting sense, and the scope of the present invention isdefined by the appended claims and their equivalents.

Traditional pacemakers allow for pacing and sensing vectors from withinsingle cardiac chambers. These vectors are typically referred to as“unipolar” and “bipolar”, depending upon the relative proximity of theelectrodes being used in the pacing and/or sensing. Unipolar and/orbipolar sensing and pacing can be performed within either the atrialchambers or the ventricular chambers of the heart.

FIG. 1 provides an illustration of unipolar and bipolar pacing andsensing vectors. In FIG. 1, there is shown an implantable pulsegenerator 100 coupled to a first cardiac lead 104 and a second cardiaclead 108. Each of the first cardiac lead 104 and the second cardiac lead108 includes a proximal end (110 for the first lead 104 and 112 for thesecond lead 108) and a distal end (114 for the first lead 104 and 116for the second lead 108). The first lead 104 further includes rightventricular electrodes that include a first right ventricular electrode118 and a second right ventricular electrode 120. The first electrode118 is shown positioned at the distal end 114 (at the tip of the lead)and the second electrode 120 is spaced proximal the first electrode 118to allow for both electrodes to be positioned in the right ventricle122. The second lead 108 further includes a first atrial sensing/pacingelectrode 126 and a second atrial sensing/pacing electrode 128. Thefirst electrode 126 is shown positioned at the distal end 116 (at thetip of the lead) and the second electrode 128 is spaced proximal thefirst electrode 126 to allow for both electrodes to be positioned in theright atrium 130. The cardiac leads 104 and 108 further includeinsulated conductors that extend between each of the electrodes andconnectors at the proximal ends 110 and 112 of the first and secondleads 104 and 108. The connectors allow each of the electrodes (118,120, 126 and 128) to be coupled to electronic control circuitry withinthe implantable pulse generator 100.

The electronic control circuitry is used to sense cardiac signals and todeliver pacing pulses through the electrodes. A bipolar vector for achamber is only available when a lead with at least two electrodes isimplanted in, or near, a chamber of the heart. In FIG. 1, each of thefirst lead 104 and the second lead 108 are shown with at least twoelectrodes implanted within a chamber of the heart. With respect to thefirst lead 104, the electronic control circuitry is used to sense and/orpace either in a unipolar or a bipolar mode. Vector line 134 indicateseither a unipolar pacing pulse or a unipolar cardiac signal between oneof the first or second electrodes 118 or 120 and the housing 136 of theimplantable medical device 100. In an alternative embodiment, vectorline 138 indicates a bipolar pacing pulse or a bipolar cardiac signalsensed between the first and second electrodes 118 and 120 on the firstlead 104.

With respect to the second lead 108, the electronic control circuitry isused to sense and/or pace either in a unipolar or a bipolar mode. Vectorline 140 indicates either a unipolar pacing pulse or a unipolar cardiacsignal between one of the first or second electrodes 126 or 128 and thehousing 136 of the implantable medical device 100. In an alternativeembodiment, vector line 144 indicates a bipolar pacing pulse or abipolar cardiac signal sensed between the first and second electrodes126 and 128 on the second lead 108. Different combinations of unipolarand bipolar sensing and pacing from each of the first lead 104 and thesecond lead 108 are programmed into the electronic control circuitrythrough the use of a medical device programmer 150.

In addition to the sensing and pacing vectors described above, it hasbeen found that additional sensing and pacing vectors within and/orbetween cardiac chambers have benefits to providing treatment to apatient. In one embodiment, the present subject matter allows foradditional sensing and/or pacing vectors between (e.g., left ventricularchamber and right ventricular chamber, left ventricular chamber andright atrial chamber, left atrial chamber and right atrial chamber) andwithin cardiac chambers when one or more cardiac leads are implanted inthe left atrium and/or left ventricular region in addition to leadsbeing implanted in the right ventricle and/or right atrium.

FIG. 2 shows one embodiment of an apparatus 200 according to the presentsubject matter. In FIG. 2, the apparatus 200 includes a first lead 204and a second lead 226. The first lead 204 has a proximal end 205 and adistal end 206 and includes a lead connector 207 having one or moreconnector terminals and a lead body 208. In one embodiment, examples ofthe lead connector 207 and connector terminals include, but are notlimited to, LV-1, IS-1 UNI or IS-1 BI. Other lead connectors andconnector terminals are possible. The lead 204 releasably attaches to animplantable pulse generator 210.

In one embodiment, the lead 204 is adapted to be inserted into andpositioned within the right ventricle 214 and the right atrium 215 ofthe heart 216. The lead 204 includes right ventricular electrodes thatinclude a first right ventricular electrode 218 and a second rightventricular electrode 219. In one embodiment, the first and second rightventricular electrodes 218 and 219 are adapted to be positioned in theright ventricular region 214. In an additional embodiment, the firstright ventricular electrode 218 is a defibrillation coil electrode andthe second right ventricular electrode 219 is a distal tipsensing/pacing electrode. In addition to the first and second rightventricular electrodes, the first lead 204 further includes additionalelectrodes, such as a first supraventricular electrode 220, where thefirst supraventricular electrode 220 is a defibrillation coil electrode.

One example of the first lead 204 is an endocardial lead sold under thetrademark ENDOTAK (Cardiac Pacemaker, Inc./ Guidant Corporation, St.Paul, Minn.), which is a tripolar, endocardial lead featuring a poroustip electrode. In one embodiment, the tip electrode 219 is placed in theapex of the right ventricle and serves as the cathode for intracardiacright ventricular electrogram rate sensing and pacing. Additionally, thetwo defibrillation coil electrodes serve as either an anode or a cathodefor rate sensing and/or morphology sensing and for defibrillation. Thepresent subject matter, however, uses the electrodes as either anodes orcathodes depending upon the programmed pacing and sensing vectordirection.

The lead connector 207 electrically connects electrodes 218, 219 and 220via conductors within the lead body 208 to the implantable pulsegenerator 210. The implantable pulse generator 210 contains controlcircuitry that receive cardiac signals sensed with the electrodes andgenerates pacing pulses to be delivered with the electrodes. Theelectronic control circuitry within the implantable pulse generator 210also analyzes and detects certain types of arrhythmias and providespacing pulses, cardioversion and/or defibrillation pulses to correct forthem.

The apparatus 200 further includes a second lead 226, where the secondlead 226 has a lead body 230 having a proximal end 232, a distal end 234and includes a lead connector 235 having one or more connectorterminals. In one embodiment, examples of the lead connector 235 andconnector terminals include, but are not limited to, LV-1, IS-1 UNI orIS-1 BI. Other lead connectors and connector terminals are possible.

The second lead 226 further includes a first left ventricular electrode236 and a second left ventricular electrode 238, where both the firstand second left ventricular electrodes 236 and 238 are adapted to bepositioned adjacent the left ventricle 240 via the coronary vasculature.In one embodiment, the first and second left ventricular electrodes 236and 238 are pacing/sensing electrodes, where the first electrode 236 andthe second electrode 238 are ring electrodes that either completely orpartially encircles lead body 230. Alternatively, the second electrode238 is a tip electrode positioned at the distal end 234 of the lead 226.

In one embodiment, the second lead 226 is adapted to be inserted throughthe coronary sinus vein 242 and through the great cardiac vein, or othercoronary branch vein, to position the ventricular electrodes 236 and 238adjacent the left ventricle 240 of the heart 216. In an alternativeembodiment, the second lead 226 is an epicardial lead, where theelectrodes on the lead 226 are positioned epicardially adjacent the leftventricle of the heart.

The lead 226 is releasably attached to the implantable pulse generator210, where the connector terminals couple the ventricular electrodes 236and 238 via lead conductors to the electronic control circuitry withinthe implantable pulse generator 210. The control circuitry within theimplantable pulse generator 210 receives cardiac signals sensed throughthe use of the electrodes 236 and 238 and generates pacing pulses to bedelivered through the use of the electrodes.

Sensing and pacing with electrodes 218, 219, 220, 236 and 238 and thehousing of the implantable pulse generator 210 is a programmable featureof the control circuitry within the pulse generator 210. In oneembodiment, programming the sensing and pacing vectors is accomplishedthrough the use of a medical device programmer 239. The medical deviceprogrammer 239 is used to program specific pacing and sensing vectorsthat use one or both electrodes 236 and 238 in conjunction withdifferent combinations of electrodes 218, 219, 220 and the housing ofthe implantable pulse generator 210.

In one embodiment, either of the ventricular electrodes 236 or 238 isused in unipolar sensing and pacing between the electrode (236 or 238)and the housing 210. Examples of these sensing and pacing vectors areshown generally at 250. In one example, the control circuitry of thepulse generator 210 is programmed to switch from unipolar sensing andpacing between one of the two electrodes 236 or 238 and the housing tounipolar sensing and pacing between the other electrode of 236 or 238and the housing. In an additional embodiment, both ventricularelectrodes 236 and 238 are used in unipolar sensing and pacing betweenthe electrodes 236 and 238 and the housing 210. Alternatively, a bipolarsensing and pacing vector occurs between the two electrodes 236 and 238,where either 236 or 238 is the anode and the other electrode is thecathode.

In one embodiment, the electrodes 236 and 238 are used in sensing andpacing between the left and right ventricles of the heart. For example,one or both of the two electrodes 236 or 238 is used to sense cardiacsignals and provide pacing pulses between the electrode(s) 236 and/or238 and the first supraventricular electrode 220.

In one embodiment, this pacing sensing vector is shown generally at 252.Alternatively, one or both of the two electrodes 236 and/or 238 is usedto sense cardiac signals and provide pacing pulses between theelectrode(s) 236 and/or 238 and the first right ventricular electrode218. In one embodiment, this pacing sensing vector is shown generally at254. In addition, one or both of the two electrodes 236 and/or 238 isused to sense cardiac signals and provide pacing pulses between theelectrode(s) 236 and/or 238 and the second right ventricular electrode219. In one embodiment, this pacing sensing vector is shown generally at255. Pacing and sensing vectors 252, 254 and 255 are referred to hereinas “extended” bipolar pacing/sensing vector, as the pacing and sensingoccurs between implanted electrodes across a larger portion of the heartthan is typical with a traditional bipolar pacing/sensing vector.

In one embodiment, electrodes 218, 219, 220, 236 and 238 are createdfrom either platinum, platinum-iridium alloys or alloys which caninclude cobalt, iron, chromium, molybdenum, nickel and/or manganese. Inaddition, the second right ventricular electrode 219 and the second leftventricular electrode 238 are porous electrodes. Alternatively, thesecond right ventricular electrode 219, the first left ventricularelectrode 236, and the second left ventricular electrode 238 are ringelectrodes that either partially or fully encircle their respective leadbodies, 208 or 230, as previously discussed. In addition, the secondright ventricular electrode 219 further includes a helical screw forpositive fixation of the lead 204.

In one embodiment, the lead bodies 208 and 230 are formed of abiocompatible polymer such as silicone rubber and/or polyurethane. Thelead bodies 208 and 230 further includes one or more lumens which areadapted to receive a stylet, or guidewire, for guiding and implantingthe leads 204 and 226. In one embodiment, the lead bodies 208 and 230include a lumen that extends from an opening at the proximal end of thelead to the distal end of the lead to allow the lead to be controlledthrough the use of the stylet, or guidewire. In one embodiment, thestylet lumen is formed from a lead conductor extending from theconnector terminal and the proximal end of the lead, 204 and 226 to adistal most electrode on the lead (e.g., the second right ventricularelectrode 219 and the second left ventricular electrode 238).

FIG. 3 shows one embodiment of control circuitry 300, as previouslymentioned, for an implantable pulse generator 302. In the presentembodiment, the implantable pulse generator 302 is adapted to receivethe first and second leads (e.g., 204 and 226), as discussed.

The control circuitry 300 is contained within a hermetically sealedhousing 304. The housing 304 is electrically conductive and acts as areference electrode in unipolar pacing and sensing, as will be describedbelow. The pulse generator 302 further includes a connector block 306that receives the connector terminals of the cardiac leads, such as 204and 226. The connector block 306 includes contacts 308, 310, 312, 314and 316 that connect electrodes 220, 218, 219, 238 and 236,respectively, to sense amplifiers 320 and 326.

In one embodiment, an output from amp 320 is shown coupled to a rightventricular activity sensor 328 to allow for a bipolar cardiac signal tobe sensed from the right ventricle 214 (FIG. 2) between the first rightventricular electrode 218 and the second right ventricular electrode 219via switch matrix 332. In this embodiment, the extended bipolar crosschamber sensing is accomplished by the controller 340 configuring theswitch matrix 332 such that the left ventricular activity sensor 334receives an extended bipolar cardiac signal sensed between the secondleft ventricular electrode 238 and the first right ventricular electrode218. Alternatively, the left ventricular activity sensor 334 receivesthe extended bipolar cardiac signal sensed between the first leftventricular electrode 236 and the first right ventricular electrode 218.The left ventricular activity sensor 334 also receives extended bipolarcardiac signal sensed between the second left ventricular electrode 238and the first supraventricular electrode 220, in addition to an extendedbipolar cardiac signal sensed between the first left ventricularelectrode 236 and the first supraventricular electrode 220. In addition,the left ventricular activity sensor 334 receives the extended bipolarcardiac signal sensed between the first and second left ventricularelectrodes 236 and 238 and the first right ventricular electrode 218.Alternatively, the left ventricular activity sensor 334 receives theextended bipolar cardiac signal sensed between the first and second leftventricular electrodes 236 and 238 and the second right ventricularelectrode 219. Which combination of extended bipolar cardiac signals aresensed depends upon the sensing vectors programmed into the switchmatrix 332 by control circuitry 300. FIG. 3 also shows the output fromamp 326 coupled to a left ventricular activity sensor 334 to allow for abipolar cardiac signal to be sensed from the left ventricle 240 (FIG. 2)between the first and second left ventricular electrodes 236 and 238.

The control circuitry 300 further includes a controller 340, where thecontroller 340 receives the cardiac signals from the sensing circuits328 and 334 and analyzes the cardiac signals to determine when and if todeliver electrical energy pulses to the heart. In one embodiment, thecontroller 340 is a microprocessor, however, other circuitry under thecontrol of software and/or firmware may be used as the controller 340.

In one embodiment, the controller 340 implements one or more analysisprotocols stored in a memory 344 to analyze one or more of the sensedcardiac signals and to provide pacing, cardioversion and/ordefibrillation therapy to one or more chambers of the heart undercertain predetermined conditions. Memory 344 is also used to store oneor more sensed cardiac signals to be downloaded to a medical deviceprogrammer 348 for analysis. In one embodiment, the control circuitry300 communicates with the medical device programmer 348 through areceiver/transmitter 350, where cardiac signals, programs and operatingparameters for the programs for the implantable medical device aretransmitted and received through the use of the programmer 348 and thereceiver/transmitter 350. Power for the control circuitry is supplied bya battery 354.

The controller 340 further controls a pace output circuit 360 and adefibrillation output circuit 364 to provide pacing, cardioversionand/or defibrillation therapy to one or more chambers of the heart undercertain predetermined conditions. In one embodiment, the pace outputcircuit 360 is coupled to contacts 308, 310, 312, 314 and 316 via switchmatrix 332 to allow for bipolar pacing between electrodes 218 and 219,and extended bipolar pacing between electrodes 236 and/or 238 and 218,219 or 220, as previously described. In an additional, extended bipolarpacing and sensing occurs between electrodes 236 and 238, electricallycoupled in common, and electrode 218, 219 or 220. In one embodiment,electrodes 236 and/or 238 are the cathode and electrodes 218, 219 and/or220 are used as the anode in the extended bipolar pacing and sensing.Alternatively, electrodes 236 and/or 238 are the anode and electrodes218, 219 and/or 220 are used as the cathode in the extended bipolarpacing and sensing. In an additional embodiment, when bipolar pacingoccurs between electrodes 218 and 219, electrode 218 is the cathode andelectrode 219 is the anode.

In addition to the extended bipolar sensing and pacing, electrode 236and/or 238 are used in conjunction with the conductive housing 304 ofthe implantable pulse generator to allow for unipolar sensing and pacingbetween either of electrodes 236 or 238 and the housing 304. In anadditional embodiment, the described polarity of the electrodes used inthe bipolar pacing and sensing is reversed to allow for additionaloptions in providing therapy to a patient.

The different combinations of the pacing and sensing vectors areprogrammable features that are selected and implemented in theimplantable pulse generator 302 through the use of the medical deviceprogrammer 348. Thus, different combinations of pacing and sensingvectors (as described above) are selected and programmed based on eachpatient's specific needs. In addition, the programmable nature of thesensing and pacing vectors described herein allows for one or more ofthe sensing and/or pacing vectors to be altered based on sensed cardiacsignals and the response to the pacing pulses delivered to the patient'sheart.

FIG. 4 shows an additional embodiment of an apparatus 400 according tothe present subject matter. In FIG. 4, the apparatus 400 includes afirst lead 204, as described above for FIG. 2. FIG. 4 further includes asecond lead 404, where the second lead 404 includes a plurality ofelectrodes. In one embodiment, the second lead 404 includes a first leftventricular electrode 408, a second left ventricular electrode 412 and athird left ventricular electrode 416.

Lead 404 includes a lead connector 418 having connector terminals forcoupling the electrodes 408, 412 and 416 via conductors within the leadbody to the control circuitry within the implantable pulse generator420. In one embodiment, the electrodes 408, 412 and 416 are adapted tobe positioned adjacent the left ventricle 430 via the coronaryvasculature. In one embodiment, the first, second and third leftventricular electrodes 408, 412 and 416 are pacing/sensing electrodes,where the electrodes are all ring electrodes that either completely orpartially encircles lead body, or are a combination of ring electrodesand distal tip electrode positioned at the distal end of the lead 404.In addition, the lead body of the lead 404 forms a helix that is adaptedto allow for the electrodes 408, 412 and 416 to better contact thecardiac tissue adjacent the left ventricle of the heart.

In one embodiment, the first and second left ventricular electrodes 408and 412 are electrically connected in common, where pacing and sensingsignals occur between combinations of the first and second leftventricular electrodes 408 and 412, in common, and the third leftventricular electrode 416. In an alternative embodiment, the first andsecond left ventricular electrodes 408 and 412 both have the sameelectrical polarity (e.g., anode or cathode), but are not electricallycoupled in common. Thus, each electrode 408 and 412 is electricallyisolated, but has the same electrical polarity. The control circuitrywithin the implantable pulse generator 420 then controls each electrodefor delivering pacing signals and sensing cardiac signals to the heart.In one embodiment, this allows the control circuitry to individuallyadjust the output of one or both the electrodes 408 and 412 based on thepacing threshold of the patient.

In an additional embodiment, the control circuitry is programmable toselect and switch between sensing unipolar cardiac signal and/ordelivering unipolar pacing pulses between each electrodes 408, 412 or416 and the housing of the implantable pulse generator 420.Additionally, the control circuitry is also programmable to select andswitch between sensing extended bipolar signals and/or deliveringextended bipolar pacing pulses between each electrodes 408, 412 or 416and either the first right ventricular electrode 218, the second rightventricular electrode 219 or the first supraventricular electrode 220.

FIG. 5 shows an additional embodiment of an apparatus 500 according tothe present subject matter. In FIG. 5, the apparatus 500 includes thefirst lead 104, as described above for FIG. 1, and lead 226, asdescribed above for FIG. 2. This embodiment allows for combinations ofelectrodes 118, 120 of the first lead 104 and electrodes 236 and 238 ofthe second lead 226 to be programmed to sense cardiac signals and/ordeliver pacing pulses between any number of electrode combinations. Forexample, extended bipolar cardiac signals are sensed between and/orpacing pulses are delivered between electrode 236 and electrode 118and/or 120, and/or extended bipolar cardiac signals are sensed betweenand/or pacing pulses are delivered between electrode 238 and electrode118 and/or 120. The control circuitry of the implantable pulse generator504 is programmable to select and switch between sensing unipolarcardiac signal and/or delivering unipolar pacing pulses between eachelectrodes 118, 120, 236 or 238 and the housing of the implantable pulsegenerator 504. Additionally, the control circuitry is also programmableto select and switch between sensing unipolar cardiac signal and/ordelivering unipolar pacing pulses between each electrodes 236 and 238and either electrode 118 or 120.

In an additional embodiment, the connector blocks of any of theimplantable pulse generators described above can further include areference electrode for use in sensing unipolar cardiac signals anddelivering unipolar pacing pulses between any of the aforementionedelectrodes (e.g., 118, 120, 218, 219, 220, 236, 238, 408, 412 or 416).An example of the connector block electrode is shown in FIG. 5 at 510.

FIG. 6 shows one embodiment of a method 600 according to one aspect ofthe present subject matter. At 610, a first cardiac lead having at leasta first supraventricular electrode is implanted within a heart. In oneembodiment, the first supraventricular electrode is positioned withinthe right atrium of the heart and/or a major vein leading to the rightatrium. At 620, a second cardiac lead having at least a first leftventricular electrode and a second left ventricular electrode isimplanted within a heart. In one embodiment, the first and second leftventricular electrodes are positioned in a left ventricular region ofthe heart.

Specific examples of the first supraventricular electrode and the firstand second left ventricular electrodes were presented above. Theseexamples, however, are not intended to be limiting and differentexamples of the first supraventricular electrode and the first andsecond left ventricular electrodes are possible. These additionalexamples include, but are not limited to, the first supraventricularelectrode taking the form of a pacing/sensing electrode, such as a ringelectrode. Additionally, one or both of the left ventricular electrodescan take the form of a coil electrode that can be used in conjunctionwith any of the aforementioned structures for the first supraventricularor ventricular electrodes.

At 630, pacing pulse vectors and sensing vectors are programmed betweenone or more of the first left ventricular electrode and the second leftventricular electrode, and the first supraventricular electrode in theright atrial region. At 640, pacing pulses are delivered between thefirst and/or second left ventricular electrode in the left ventricularregion and the first supraventricular electrode in the right atrialregion, according to the programmed pacing pulse vectors. In oneembodiment, the first and/or second left ventricular electrode is usedas the cathode, while the first supraventricular electrode is used asthe anode. In an alternative embodiment, the first supraventricularelectrode is used as the cathode, while the first and/or the second leftventricular electrode is used as the anode.

In addition to providing pacing pulses between the first and/or secondleft ventricular electrode and the first supraventricular electrode,sensing vectors between the first left ventricular electrode and/or thesecond left ventricular electrode, and the first supraventricularelectrode are sensed at 650 according to the programmed sensing vector.In one embodiment, the cardiac signal is sensed where the first and/orsecond left ventricular electrode is an anode and the firstsupraventricular electrode is a cathode. In an alternative embodiment,the cardiac signal is sensed where the first supraventricular electrodeis an anode and the first and/or second left ventricular electrode is acathode. In an additional embodiment, the housing of an implantablepulse generator is conductive and is used in an electrode in common withthe first supraventricular electrode, as previously discussed.

FIG. 7 shows one embodiment of a method 700 according to one aspect ofthe present subject matter. At 710, a first cardiac lead having at leasta right ventricular electrode is implanted within a heart. In oneembodiment, the right ventricular electrode is either a defibrillationelectrode, such as the first right ventricular electrode 218, or apace/sense electrode, such as the second right ventricular electrode219. These examples, however, are not intended to be limiting anddifferent examples of the right ventricular electrode are possible. Inone embodiment, the right ventricular electrode is positioned within theright ventricle of the heart.

At 720, a second cardiac lead having at least a first left ventricularelectrode and a second left ventricular electrode is implanted within aheart. In one embodiment, the first and second left ventricularelectrodes are positioned in a left ventricular region of the heart. Inone embodiment, the first and second left ventricular electrodes are aspreviously described. These examples, however, are not intended to belimiting and different examples of the first and second left ventricularelectrodes are possible. For example, one or both of the leftventricular electrodes can take the form of a coil electrode that can beused in conjunction with any of the aforementioned structures for thesupraventricular or ventricular electrodes.

At 730, pacing pulse vectors and sensing vectors are programmed betweenone or more of the first and second left ventricular electrodes, and theright ventricular electrode. At 740, pacing pulses are delivered betweenthe first and/or second left ventricular electrode and the rightventricular electrode, according to the programmed pacing pulse vectors.In one embodiment, the first and/or second left ventricular electrode isused as the cathode, while the right ventricular electrode is used asthe anode. In an alternative embodiment, the right ventricular electrodeis used as the cathode, while the first and/or the second leftventricular electrode is used as the anode.

In addition to providing pacing pulses between the first and/or secondleft ventricular electrode and the right ventricular electrode, sensingvectors between one, or both, of the first and second left ventricularelectrodes and the right ventricular electrode are sensed at 750according to the programmed sensing vector. In one embodiment, thecardiac signal is sensed where the first and/or second left ventricularelectrode is an anode and the right ventricular electrode is a cathode.In an alternative embodiment, the cardiac signal is sensed where theright ventricular electrode is an anode and the first and/or second leftventricular electrode is a cathode. In an additional embodiment, thehousing of an implantable pulse generator is conductive and is used inan electrode in common with the right ventricular electrode, aspreviously discussed.

FIG. 8 shows one embodiment of a method 800 according to one aspect ofthe present subject matter. At 810, a first cardiac lead having at leasta first supraventricular electrode and a first ventricular electrode isimplanted within a heart.

In one embodiment, the first supraventricular electrode is positionedwithin the right atrium of the heart, while the first ventricularelectrode is positioned within the right ventricle of the heart. In oneembodiment, the right ventricular electrode is either a defibrillationelectrode, such as the first right ventricular electrode 218, or apace/sense electrode, such as the second right ventricular electrode219. These examples, however, are not intended to be limiting anddifferent examples of the right ventricular electrode are possible. At820, a second cardiac lead having at least a first left ventricularelectrode and a second left ventricular electrode is implanted within aheart. In one embodiment, the first and second left ventricularelectrodes are positioned in a left ventricular region of the heart.

Specific examples of the first supraventricular and ventricularelectrodes and the first and second left ventricular electrodes werepresented above. These examples, however, are not intended to belimiting and different examples of the first supraventricular andventricular electrodes and the first and second left ventricularelectrodes are possible. These additional examples include, but are notlimited to, the first supraventricular or ventricular electrode takingthe form of a pacing/sensing electrode, such as a ring electrode.Additionally, one or both of the left ventricular electrodes can takethe form of a coil electrode that can be used in conjunction with any ofthe aforementioned structures for the first supraventricular orventricular electrodes.

At 830, pacing pulse vectors and sensing vectors are programmed betweenone or more of the first left ventricular electrode and/or the secondleft ventricular electrode, and the first supraventricular electrode inthe right atrial region and the right ventricular electrode in the rightventricle. At 840, pacing pulses are delivered between either the firstand/or second left ventricular electrode and the first supraventricularelectrode and/or the first right ventricular electrode, according to theprogrammed pacing pulse vectors. In one embodiment, the first and/orsecond left ventricular electrode is used as the cathode, while thefirst supraventricular and/or the right ventricular electrode is used asthe anode. In an alternative embodiment, the first supraventricularand/or right ventricular electrode is used as the cathode, while thefirst and/or the second left ventricular electrode is used as the anode.

In addition to providing pacing pulses between the first and/or secondleft ventricular electrode and the first supraventricular electrodeand/or right ventricular electrode, sensing vectors between one or bothof the first and/or second left ventricular electrodes, and the firstsupraventricular and/or the right ventricular electrode are sensed at850 according to the programmed sensing vector. In one embodiment, thecardiac signal is sensed where the first and/or second left ventricularelectrode is an anode and the first supraventricular electrode and/orthe right ventricular electrode is a cathode. In an alternativeembodiment, the cardiac signal is sensed where the firstsupraventricular electrode and/or the right ventricular electrode is ananode and the first and/or second left ventricular electrode is acathode. In an additional embodiment, the housing of an implantablepulse generator is electrically conductive and used as an electrode incommon with the first supraventricular electrode and/or the rightventricular electrode, as previously discussed.

FIG. 9 shows one embodiment of a method 900 according to an additionalaspect of the present subject matter. At 910, a first cardiac leadhaving at least a first right ventricular electrode and a second rightventricular electrode is implanted within a heart. In one embodiment,the first and second right ventricular electrodes are positioned withinthe right ventricle of the heart. Specific examples of the first andsecond right ventricular electrodes were presented above, where thefirst right ventricular electrode is a defibrillation coil electrodepositioned in a right ventricular region, and the second rightventricular electrode is a pacing/sensing electrode located at or nearthe distal tip of the lead and positioned in an apex of the rightventricular region. At 920, a pacing level pulse is delivered from afirst ventricular defibrillation electrode as a cathode to a firstventricular pacing/sensing electrode as an anode.

FIG. 10 shows an additional embodiment of control circuitry 1000, aspreviously mentioned, for an implantable pulse generator 1002. In thepresent embodiment, the implantable pulse generator 1002 is adapted toreceive the first and second leads (e.g., 204 and 226, 204 and 404, 104and 226), as previously discussed.

The control circuitry 1000 is contained within a hermetically sealedhousing 1004. The housing 1004 is electrically conductive and acts as areference electrode in unipolar pacing and sensing, as will be describedbelow. The pulse generator 1002 further includes a connector block 1006that receives the connector terminals of the cardiac leads, such as 204and 226, 204 and 404, or 104 and 226. In one embodiment, the connectorblock 1006 includes contacts 1008, 1010, 1012, 1014 and 1016 thatconnect electrodes 220, 218, 219, 238 and 236, respectively, to senseamplifiers 1020, 1022, 1024 and 1026.

In one embodiment, an output from amp 1020 is shown coupled to a rightventricular activity sensor 1028 to allow for a bipolar cardiac signalto be sensed from the right ventricle 214 (FIG. 2) between the firstright ventricular electrode 218 and the second right ventricularelectrode 219. In addition, an output from amps 1022 and 1024 is showncoupled to an extended bipolar cross chamber sensor 1030. In thisembodiment, the extended bipolar cross chamber sensor 1030 receives anextended bipolar cardiac signal sensed between the second leftventricular electrode 238 and the first right ventricular electrode 218.Alternatively, the extended bipolar cross chamber sensor 1030 receivesthe extended bipolar cardiac signal sensed between the first leftventricular electrode 236 and the first right ventricular electrode 218.The extended bipolar cross chamber sensor 1030 also receives extendedbipolar cardiac signal sensed between the second left ventricularelectrode 238 and the first supraventricular electrode 220, in additionto an extended bipolar cardiac signal sensed between the first leftventricular electrode 236 and the first supraventricular electrode 220.In addition, the extended bipolar cross chamber sensor 1030 receives theextended bipolar cardiac signal sensed between the first and second leftventricular electrodes 236 and 238 and the first right ventricularelectrode 218. Alternatively, the extended bipolar cross chamber sensor1030 receives the extended bipolar cardiac signal sensed between thefirst and second left ventricular electrodes 236 and 238 and the secondright ventricular electrode 219. Which combination of extended bipolarcardiac signals are sensed depends upon the sensing vectors programmedinto the control circuitry 1000. FIG. 10 also shows an output from amp1026 coupled to a left ventricular activity sensor 1034 to allow for abipolar cardiac signal to be sensed from the left ventricle 240 (FIG. 2)between the first and second left ventricular electrodes 236 and 238.

The control circuitry 1000 further includes a controller 1040, where thecontroller 1040 receives the cardiac signals from the sensing circuits1028, 1030 and 1034 and analyzes the cardiac signals to determine whenand if to deliver electrical energy pulses to the heart. In oneembodiment, the controller 1040 is a microprocessor, however, othercircuitry under the control of software and/or firmware may be used asthe controller 1040.

In one embodiment, the controller 1040 implements one or more analysisprotocols stored in a memory 1044 to analyze one or more of the sensedcardiac signals and to provide pacing, cardioversion and/ordefibrillation therapy to one or more chambers of the heart undercertain predetermined conditions. Memory 1044 is also used to store oneor more sensed cardiac signals to be downloaded to a medical deviceprogrammer 1048 for analysis. In one embodiment, the control circuitry1000 communicates with the medical device programmer 1048 through areceiver/transmitter 1050, where cardiac signals, programs and operatingparameters for the programs for the implantable medical device aretransmitted and received through the use of the programmer 1048 and thereceiver/transmitter 1050. Power for the control circuitry is suppliedby a battery 1054.

The controller 1040 further controls a pace output circuit 1060 and adefibrillation output circuit 1064 to provide pacing, cardioversionand/or defibrillation therapy to one or more chambers of the heart undercertain predetermined conditions. In one embodiment, the pace outputcircuit 1060 is coupled to contacts 1008, 1010, 1012, 1014 and 1016 toallow for bipolar pacing between electrodes 218 and 219, and extendedbipolar pacing between electrodes 236 and/or 238 and 218, 219 or 220, aspreviously described. In an additional, extended bipolar pacing andsensing occurs between electrodes 236 and 238, electrically coupled incommon, and electrode 218, 219 or 220. In one embodiment, electrodes 236and/or 238 are the cathode and electrodes 218, 219 and/or 220 are usedas the anode in the extended bipolar pacing and sensing. Alternatively,electrodes 236 and/or 238 are the anode and electrodes 218, 219 and/or220 are used as the cathode in the extended bipolar pacing and sensing.In an additional embodiment, when bipolar pacing occurs betweenelectrodes 218 and 219, electrode 218 is the cathode and electrode 219is the anode.

In addition to the extended bipolar sensing and pacing, electrode 236and/or 238 are used in conjunction with the conductive housing 1004 ofthe implantable pulse generator to allow for unipolar sensing and pacingbetween either of electrodes 236 or 238 and the housing 1004. In anadditional embodiment, the described polarity of the electrodes used inthe bipolar pacing and sensing is reversed to allow for additionaloptions in providing therapy to a patient.

The different combinations of the pacing and sensing vectors areprogrammable features that are selected and implemented in theimplantable pulse generator 1002 through the use of the medical deviceprogrammer 1048. Thus, different combinations of pacing and sensingvectors (as described above) are selected and programmed based on eachpatient's specific needs. In addition, the programmable nature of thesensing and pacing vectors described herein allows for one or more ofthe sensing and/or pacing vectors to be altered based on sensed cardiacsignals and the response to the pacing pulses delivered to the patient'sheart.

In addition to the apparatus and methods described for providing pacingand sensing across ventricular regions of the heart, the present subjectmatter can also be used in a system having electrodes implanted in andaround the supraventricular region of the heart. So, the present subjectmatter could be used to sense and pace bipolarly across the right andleft atrium of the heart.

In addition to the apparatus and methods for providing pacing andsensing across the regions of the heart using two left ventricularelectrodes, the present subject matter can also use a cardiac leadhaving a plurality of left ventricular electrodes, such as those shownand described in the example of FIG. 4.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. It should be noted that embodiments discussed indifferent portions of the description or referred to in differentdrawings can be combined to form additional embodiments of the presentinvention. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. An implantable medical device (IMD) including anon--transitory processor-readable medium comprising instructions that,when performed by the processor cause the TIVI) to: receive informationabout a selection of a combination of ventricular electrodes for use indelivery of a cardiac pacing pulse, the selection including anindication of a cathode electrode and an anode electrode; and controlgeneration of a cardiac pacing pulse for delivery across t lecombination of electrodes according to the selection; and wherein theselectable combination includes an anode electrode and a cathodeelectrode, the anode electrode located along a firstintravascularly-delivered lead within a great vein, the cathodeelectrode located along a separate second intravascularly-deliveredlead.
 2. The IMD of claim 1, wherein the cathode electrode is locatedalong the separate second intravascular-delivered lead disposed at alocation different than the great vein where the firstintravascularly-delivered lead is located.
 3. The IMD of claim 2,wherein the selectable combination includes a cathode electrodecomprising a defibrillation electrode located along the separate secondintravascularly-delivered lead.
 4. The IMD of claim 1, wherein thenon-transitory processor-readable medium includes instructions thatcause the IMD to sense cardiac electrical activity using the combinationof electrodes according to the selection.
 5. The IMD of claim 4, whereinthe non-transitory processor-readable medium includes instructions thatcause the IMD to select a different combination of an anode electrodeand a cathode electrode in response to the sensed cardiac electricalactivity meeting a specified criterion.
 6. The IMD of claim
 1. whereinthe non-transitory processor-readable medium includes instructions thatcause the IMD to: receive information about a selection of a second,different, combination of electrodes; and sense cardiac electricalactivity using the second, different, combination of electrodes.
 7. Animplantable medical device (IMD) including a non-transitoryprocessor-readable medium comprising instructions that, when performedby the processor cause the IMD to: receive information about a selectionof a combination of ventricular electrodes for use in delivery of acardiac pacing pulse, the selection including an indication of a anodeelectrode and multiple commonly connected cathode electrodes; andcontrol generation of a cardiac pacing pulse for delivery across thecombination of electrodes according to the selection; and wherein theselectable combination includes an anode electrode and multiplecommonly-connected cathode electrodes, the anode electrode located alona first intravascularly-delivered lead within a great vein.
 8. The IMDof claim 7, wherein the selectable combination includes multiplecommonly-connected cathode electrodes located in or near a differentheart chamber than a heart chamber most closely associated with theselected anode electrode.
 9. The IMD of claim 7, wherein the selectablecombination of multiple commonly-connected cathode electrodes includesat least two cathode electrodes located along the lead within the rightventricle.
 10. The IMD of claim 7, wherein the selectable combination ofmultiple commonly-connected cathode electrodes includes at least twocathode electrodes located along the lead within the great vein.
 11. TheIMD of claim 7, wherein the non-transitory processor-readable mediumincludes instructions that cause the IMD to sense cardiac electricalactivity using the combination of electrodes according to the selection.12. The IMD of claim 11, wherein the non-transitory processor-readablemedium includes instructions that cause the IMD to select a differentcombination of an anode electrode and the multiple commonly-connectedcathode electrodes in response to the sensed cardiac electrical activitymeeting a specified criterion.
 13. The IMD of claim 7, wherein thenon-transitory processor-readable medium includes instructions thatcause the IMD to: receive information about a selection of a second,different, combination of electrodes; and sense cardiac electricalactivity using the second, different, combination of electrodes.
 14. Anapparatus, comprising: an implantable medical device (MD) including acontrol circuit coupled to a pacing output circuit, the control circuitconfigured to receive information about a selection of a combination ofventricular electrodes for use in delivery of a cardiac pacing pulse,the selection including an indication of a cathode electrode and ananode electrode, and the control circuit configured to controlgeneration of a cardiac pacing pulse to be delivered via the pacingoutput circuit across the combination of electrodes according to theselection; and wherein a selectable combination includes an anodeelectrode and a cathode electrode, the anode electrode located along afirst intravascularly-delivered lead within a great vein, the cathodeelectrode located along a separate second intravascularly-deliveredlead.
 15. The apparatus of claim 14, wherein the selectable combinationincludes multiple commonly-connected cathode electrodes.
 16. Theapparatus of claim 15, wherein the selectable combination includesmultiple commonly-connected cathode electrodes located in or near adifferent heart chamber than a heart chamber most closely associatedwith the selected anode electrode.
 17. The apparatus of claim 14,further comprising an external programmer configured to receive theselection, the programmer configured to transmit information about theselection to the IMD.
 18. The apparatus of claim 14, wherein the IMDcomprises a sensing circuit coupled to the controller circuit; thesensing circuit controlled by the controller circuit, and the sensingcircuit configured to sense cardiac electrical activity using thecombination of electrodes according to the selection.
 19. The apparatusof claim 14, wherein the controller circuit is configured to receiveinformation about a selection of a second, different, combination ofelectrodes; and wherein the controller circuit is configured to controlthe sensing circuit to sense cardiac electrical activity using thesecond, different, combination of electrodes.
 20. The IMD of claim 14,further comprising a sensing circuit coupled to the control circuit, thesensing circuit configured to sense cardiac electrical activity usingthe combination of electrodes according to the selection.